The planning and pilot research activities proposed in this application are intended to build collaborative relationships and research capacity around the conduct of epidemiological research of autism spectrum disorders (ASD) in China. The Center for Autism and Developmental Disabilities Epidemiology (CADDE) at the Johns Hopkins Bloomberg School of Public Health will team with the Institute of Reproductive and Child Health (IRCH) at Peking University. CADDE is currently engaged in a number of large, population-based ASD epidemiology projects in the US and IRCH has a long track record of conducting population-based prenatal, child health, and developmental disabilities research in China, including major projects partnering with US collaborators. ASD is a severe, brain-based developmental disability whose prevalence appears to be on the rise in the developed countries but whose prevalence in China, a nation including 680 million children under age 14, is largely unknown. ASD is a very complex disorder of unknown etiology that appears to involve multiple epistatic genes and potential gene-environment interaction. Launching research efforts in populations where the genetic background and exposure distributions may differ from populations already studied should hasten progress toward revealing important heritable and nonheritable risk factors. Under the planning grant, the US-China team will: 1) develop a feasible approach for implementing an ASD prevalence study in the Weifang area of Shandong Province; 2) develop a strategy for expanding the prevalence study to a population-based etiologic study; and 3) conduct pilot research activities informing this research development. Pilot activities will include translation and adaptation of ASD screening and diagnostic tools as well as implementation of a limited-scale prevalence study in the WeiCheng District of Weifang that uses the newly adapted tools. This will allow for both field-testing of recruitment and data collection processes and evaluation of the adapted screening/diagnostic methods through expert review.